The invention relates to an electronic device for frequencies of up to two gigahertz comprising a housing containing a printed circuit, possibly with connected active and/or passive components, which printed circuit is provided with metallized tracks forming electric connecting lines which are mounted parallel to an electrically conducting plate which serves as a ground plane.
It also relates to a process for manufacturing such a device.
Such a device is used particularly for circuits for the distribution of cable television in which the signals, including those of satellite TV signals, have frequencies in the medium frequency band, of between 40 and 2050 mHz.
A device comprising electric lines mounted parallel to an electrically conducting plate is known from the document EP-A 0 222 445. The ground plane according to this document is formed in usual manner by a metallization on the rear surface of the printed circuit board. With such a device, the electric field of the line develops mainly in the material of the printed circuit board, which leads to losses and excessive mismatches at high frequencies owing to quality defects and irregularities of this material, unless a material of very high quality is used, which would be expensive.